IME, the dynamics in Indian schools, are polar opposite to the ones described here. "Nerds" tend to do well in both academics and extracurriculars. And in the majority case can also be referred to simultaneously as "Jocks". The separation between "nerds" and "jocks" into two ends of a (lunch table) spectrum is the biggest culture shock to me. The words that separate "nerds" and "jocks" don't exist in my native language's vocabulary even.
For the longest time, I believed that intelligence is a broadly applicable trait, that translates well to rapid spatial reasoning(sports), abstract reasoning(academics) and emotional awareness(social). I haven't seen even a single exception to the rule while going through the Indian school system.
While there is some truth to it. IMHO, it has to do with cultural ideals that "adults" adhere to. Academic achievement isn't celebrated culturally in US (relatively speaking).
I say that while also simultaneously acknowledging that the current Indian definition of academic achievement is disastrously narrow and breeds a culture of arrogance and intellectual insecurity.